Substitution of vegetable protein for animal protein in an individual's diet has traditionally addressed the needs of persons with food allergies or intolerance to dairy-based formula components (usually casein, whey, or lactose) and individuals who desire to limit or avoid animal protein for life style philosophy (vegetarianism) or religious beliefs and practices. As positive outcomes from research in the area of vegetable extracts in the nutritional management of disease states are published, desire to add these "added value" vegetables to individual diets has expanded in the general population.
Many of the "active components" identified in vegetables are phytoestrogens. A number of these compounds have been identified in fruits, vegetables, and whole grains commonly consumed by humans. Phytoestrogens include isoflavones which occur in a variety of leguminous plants. Soybeans are the most significant dietary sources of isoflavones. Isoflavones have been detected and identified in biological fluids of humans consuming the plant material, Due to the phenolic structure, which is similar to those of animal estrogens, these compounds exhibit weak estrogenic properties and are termed phytoestrogens. It is the isoflavones which have received the most attention and have been reviewed in great detail in "Mammalian lignans and phyto-oestrogens- Recent studies on their formation, metabolism and biological role in health and disease" by Setchell and Adlercreutz, Role of the Gut Flora in Toxicity and Cancer. New York, Academic Press, 1988; pp 315-45; "Naturally Occurring Oestrogens in Foods- A Review" by Price and Fenwick, Food Additives and Contaminants, Vol.2, No.2, pp73-106,1985; and "Dietary Phytoestrogens" by Kurzer and Xu, Annual Review of Nutrition Vol 17, 1997; pp 353-81.
Studies in humans, animals and cell culture systems suggest that dietary phytoestrogens play an important role in prevention of menopausal symptoms, osteoporosis, cancer, and heart disease. Proposed mechanisms include estrogenic and antiestrogenic effects, induction of cancer cell differentiation, inhibition of tyrosine kinase and DNA topoisomerase activities, suppression of angiogenesis and antioxidant effects. The major isoflavones occurring in plants are the glycosides of genistein, daidzein and glycitein.
Isoflavones isolated from soy have become the focus of much research in the areas of heart disease, cancer, osteoporosis and kidney diseases. This expanding knowledge in the possible role of soy and its fractions in the nutritional management of disease states has presented practical challenges for the average consumer in the market place. The primary challenge is access to good tasting products with naturally high concentrations of isoflavones.
The isoflavone contents in commercial soy raw ingredients vary depending on the levels of isoflavones in the plant variety and processing procedures. For example, approximately 90% of phytoestrogens present in soy foods are beta-glucoside conjugates of daidzein and genistein. However, in fermented soy products, the aglucones (unconjugated) are the predominant forms. The nutrient and isoflavone content of the most common available soy foods, soy ingredients and nutritionals are listed in Table 1 below.
TABLE 1 ______________________________________ Nutrient and Isoflavone Content of Different Soy Foods and Ingredients* Protein Fat g g Estimated Calories (% of (% of Isoflavone Soy food Kcal Cal.) Cal.) mg ______________________________________ Miso (1 oz) 35 2 (23) 1 (25) 10 Soybeans, cooked (1/2 149 14 (37) 8 (48) 35 cup) Soy flour (31/2 cup) 441 35 (32) 22 (45) 50 Soymilk (1 cup) 140 10 (28) 4 (26) 40 Soymilk, low-fat 120 8 (26) 3 (22) 40 (1 cup) Soy nuts, 387 34 (35) 19 (44) 50 dry roasted (1/2 cup) Soy protein isolate 94 25 (100) 1 (9) 15 (1 oz) Tempen (4 oz) 204 17 (33) 8 (35) 40 Tofu, low-fat 35 6 (68) 1 (25) 30 (3 oz) Tofu, extra-firm (3 oz) 60 6 (40) 3 (45) 45 Textured Vegetable Protein 59 11 (74%) 0 (0) 35 (1/4 cup,dry) Ensure (8 fl. oz.) 250 8.8 (14) 6.1 (22) 2.6 GeniSoy 130 14 (43) 0 (0) 14-70** (35 gm) ______________________________________ *Table adapted from US Department of Agriculture Handbook 8 **Based on GeniSoy literature which describes a typical isoflavone range from 1.0-5.0 mg isoflavone/gram soy protein, assuming 100% of the protein is soy protein containing isoflavone.
While there are a few soy-based foods available on the market today, they are not easily incorporated into an individual's diet. Accessibility of the products listed in Table 1 is an issue for most of the general population. A few of the products are starting to be stocked in standard grocery stores; however, many must be purchased in "Health Food Stores". More importantly, the taste and texture of soy products are objectionable to many individuals that have not grown up with soy protein in their diets. In addition, most of the foods in Table 1 are ingredients to be incorporated into a food dish and most individuals do not know how to cook with these ingredients. While the roasted soy nuts, which would probably be an acceptable snack food for most individuals, weigh in with a high isoflavone content, the high calorie and fat content are unacceptable for daily incorporation into an individual's diet. Soy milk is a reasonable source of isoflavones and has been used by individuals with cow milk allergies for many years and there are currently more flavors and fat content options to chose from. A serving (1 cup) of "Light" soy milk contains 3 grams of fat and 8 grams of protein in 120 total calories. No inherent vitamins and a small amount of calcium and iron (2% of the RDI) are present in soy milk. A serving (1 cup) of full fat soy milk contains 4 grams of fat and 10 grams of protein in 140 total calories. The requirement for refrigerated storage and the flavor of soy milk remain a major obstacle for the average consumer.
FDA-regulated food products began using the Daily Value as the basis for declaring nutrient content May 8, 1994. Daily Values (DVs) are a set of dietary reference values to help consumers use food label information to plan a healthy overall diet. DVs actually comprise two sets of reference values for nutrients: Daily Reference Values (DRVs) and Reference Daily Intakes (RDI).
DRVs are a set of dietary references for which no set of standards previously existed. DRVs apply to fat, saturated fat, cholesterol, carbohydrate, protein, fiber, sodium and potassium. Based on 2,000 calories a day for adults and children over 4, the DRV for fat is 65 grams; saturated fat is 20 gm; cholesterol is 300 milligrams; total carbohydrate is 300 grams; fiber is 25 grams; sodium is 2,400 milligrams; potassium is 3,500 milligrams; and protein is 50 grams.
RDIs are a set of dietary references based on the Recommended Dietary Allowances (RDA) for essential vitamins and minerals. The name "RDI" replaces the term "U.S. RDA"(Recommended Daily Allowances). Recommended Dietary Allowances (RDA) are the set of estimated nutrient allowances established by the National Academy of Sciences used as the basis for setting the U.S. RDAs. It is updated periodically to reflect current scientific knowledge.
The liquid nutritional, Ensures (Ross Products Division of Abbott Laboratories, Chicago, Ill.), a good tasting, shelf stable, ready to drink complete nutritional with a protein system that contains soy protein isolate, is an alternative to the more traditional soy foods. However, only 20% of the total protein system is soy protein isolate resulting in an isoflavone content too low to practically provide the benefit of consuming soy protein.
GeniSoy.TM. is a powdered protein shake manufactured by GeniSoy Products Co. (Fairfield, Calif.) with water processed isolated soy protein. A serving (8 oz.) of the Vanilla product contains 14 gm of soy protein, zero fat and 18 gm of total carbohydrate in 130 calories. The vitamins and minerals are fortified at 25% of the RDI with the exception of vitamin E (170% of the RDI). GeniSoy Products literature states that although the isoflavone content of GeniSoy is not tested, typical isoflavone values for water processed soy protein isolate range from 1.0 to 5.0 mg of isoflavone/gram soy protein isolate. While this vitamin and mineral fortified product provides large amounts of soy protein isolate in a single serving, it is not a complete nutritional that could be used as a sole source of nutrition due to the absence of fat in the form of essential fatty acids. Further, the inconvenience of the powder form and the soy flavor remain an issue for many consumers.
Isoflavone compounds are associated with the inherent bitter flavor of soybeans. Consequently, in the production of commercial products, such as isolates and concentrates, the focus has been traditionally to remove these materials. For example, in a conventional process for the production of a soy protein isolate, in which soy flakes are extracted with an aqueous alkaline medium, much of the isoflavones are solubilized in the extract, and remain solubilized in the whey, which is usually discarded following acid precipitation of the protein to form an isolate. Residual isoflavones left in the acid precipitated protein isolate are usually removed by exhaustive washing of the isolate. This process has been modified to maintain and enrich the isoflavone content of the vegetable isolates, concentrates, protein fiber and whey.
EP 0 647 408 by Shen, et al., teaches how to manufacture an isoflavone enriched vegetable protein isolate by extracting a vegetable protein material containing isoflavones at a pH above the isoelectric point of the material, then adjusting the pH to about the isoelectric point of the protein material resulting in a precipitate, then doing limited washing of the precipitate to provide an isoflavone enriched protein isolate.
U.S. Pat. No. 5,637,562 by J. L. Shen discloses a process to manufacture isoflavone enriched vegetable protein concentrate through an isoelectric wash of a vegetable protein material to provide a protein concentrate, which is slurried and reacted with a sufficient amount of beta-glucosidase enzyme or esterase enzyme for a time period, temperature and pH sufficient to convert at least a majority of the glucone isoflavones contained in the concentrate to aglucone isoflavones.
U.S. Pat. No. 5,352,384 by J. L. Shen discloses a process to manufacture isoflavone enriched vegetable protein fiber. The starting material is extracted at a pH above the isoelectric point of the protein material, the aqueous slurry containing the solubilized isoflavones is reacted with a beta-glucosidase to convert the isoflavones in glucone form to an aglucone isoflavone making the isoflavones less soluble, the fibrous residue is recovered to provide a vegetable fiber product which has been enriched with aglucone isoflavones.
U.S. Pat. No. 5,637,561 by J. L. Shen discloses a process to make aglucone isoflavone enriched vegetable protein whey by treating the whey stream, comprising glucone isoflavones, with a sufficient amount of beta-glucosidase enzyme or esterase enzyme or acid to convert at least a majority of the glucone isoflavones to aglucones thereby providing an aglucone enriched whey stream. The aglucone enriched whey protein is obtained by recovery of the protein.
The importance of isoflavone enriched vegetable protein sources becomes more apparent when one reviews the field of isoflavone research. Most of the human research on isoflavones has been carried out by incorporating soy products into the typical American diet or studying Asian countries where soy is a normal part of the diet. While the health benefits of soy have been attributed to isoflavones, the actual active ingredient or ingredients have yet to be identified. The level and ratio of the isoflavones in addition to other inherent components of soy may play an important role in the health benefits attributed to soy. However, there are dietary supplement patents incorporating isolated phytoestrogens into compositions for the management of osteoporosis and premenstrual syndrome.
A product containing isoflavones for the management of osteoporosis is described in U.S. Pat. No. 5,424,331 by M. Shlyankevich which discloses a pharmaceutical or dietary supplement for the treatment or prevention of osteoporosis. The composition comprises phytoestrogen compounds; dried licorice root extract; calcium, magnesium and zinc salts; beta carotene; and vitamin D and E in an acceptable inert carrier.
A product containing isoflavones for the management of premenstrual syndrome is described in U.S. Pat. No. 5,569,459 by M. Shlyankevich which discloses a pharmaceutical or dietary supplement for controlling the stimulation of estrogen production. The composition comprises phytoestrogen compounds; dried licorice root extract; a sedative selected from the group consisting of Balerian root dry extract, passion flower dry extract and Ginseng root powder; beta-carotene; pyridoxine hydrochloride; Vitamin E; calcium, magnesium and zinc salts; coumestan; and pantothenic acid in an acceptable inert carrier.
A dietary supplement for supplementing the nutritional needs of women and preventing or reducing life stage associated health risks during each of their principal adult life stages (pre-perimenopause, perimenopause and menopause, or post-menopause) is described in U.S. Pat. No. 5,654,011 by S. D. Jackson, et al. The dietary supplement comprises calcium, magnesium, boron, copper, manganese, zinc, vitamin D, E and C; iron, folic acid, vitamin B.sub.12 and B.sub.6 ; chromium, and phytoestrogens in a biologically acceptable carrier.
As discussed above, there are several soy-based products currently available to the consumer. However, they are products with unacceptable taste or mouth feel, they require special storage conditions such as refrigeration or are in powder forms requiring an additional reconstitution step before consumption. Further limitations of these products appear in their nutrient content. Their nutrient content ranges from no supplementation of vitamins and minerals to fortification at 25% of the RDI. These soy based products have not been optimized to complement the positive effects attributed to soy such as, for example, fortification of the formula to provide a calcium/phosphorous ratio sufficient to complement the effects of soy on osteoporosis; or a sodium limitation for the hypertensive individual; or an antioxidant package to complement the cancer and heart disease benefits of soy.
Clearly, there is need for a convenient, shelf stable, low fat, calcium enriched, good tasting, complete nutritional which is a soy-based product that will deliver inherent isoflavones to an individual choosing to supplement their diet with soy protein.